Synchronisation of the EDML and EDC ice cores for the last 52 kyr by volcanic signature matching

M. Severi (1) , S. Becagli (1) , E. Castellano (1) , A. Morganti (1) , R. Traversi (1) , R. Udisti (1) , U. Ruth (2) , H. Fischer (2) , P. Huybrechts (2, 3) , E. Wolff (4) , F. Parrenin (5) , P. Kaufmann (6) , F. Lambert (6) , J. P. Steffensen (7)

1 Department of Chemistry
2 AWI - Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine
3 Departement Geografie
4 BAS - British Antarctic Survey
5 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
6 CEP - Climate and Environmental Physics [Bern]
7 NBI - Niels Bohr Institute [Copenhagen]

A common time scale for the EPICA ice cores from Dome C (EDC) and Dronning Maud Land (EDML) was established. Since EDML core was not drilled on a dome, the development of the EDML1 time scale for the EPICA ice core drilled in Dronning Maud Land was carried on by creating a detailed stratigraphic link between this core and the one drilled at Dome C, dated by a simpler 1D ice-flow model. The synchronisation between the two ice cores was built via the identification of several common volcanic signatures. This paper describes the rigorous method, using the signature of volcanic sulfate, which was employed for the last 52 kyr of the record. By evaluating the ratio R of the apparent duration of temporal intervals between couples of isochrones, the depth comparison between the two cores was turned into an estimate of anomalies between the modelled EDC and EDML glaciological age models during the studied period. On average R ranges between 0.8 and 1.2 corresponding to an uncertainty within 20% in the estimate of the time duration in at least one of the two ice cores. Significant deviations of R up to 1.4–1.5 are observed between 18 and 28 kyr BP. At this step our approach is not able to unequivocally find out which of the models is affected by the errors, but assuming the thinning function at both sites and accumulation history at Dome C, which was drilled on a dome, as being correct, this anomaly can be ascribed to a complex spatial accumulation variability (which may be different at present day and in the past) and to upstream ice flow in the area of the EDML core.

Domaines: Interfaces continentales, environnement; Sciences de la Terre

M. Severi, S. Becagli, E. Castellano, A. Morganti, R. Traversi, et al.. Synchronisation of the EDML and EDC ice cores for the last 52 kyr by volcanic signature matching. Climate of the Past Discussions, 2007, 3 (2), pp.409-433. ⟨hal-00330727⟩